New Delhi, Nov. 1 -- As soon as you enter Mariani town in Upper Assam, a lopsided board points heavenwards, telling you the distance to the Hoollongapar Gibbon Sanctuary. It's best not to take the directions literally-instead, follow the railway track to the protected forest area. Hoollongapar is like a rich green island, set amidst acres of lush tea plantations. I am there for a basic field session by the scientific and industrial research not-for-profit organization Aaranyak-rudimentary first steps towards becoming a guide, with initiation into the history of the sanctuary and an understanding of its conservation needs.

Walking through the sanctuary, located on the south bank of the Brahmaputra riverin Jorhat district, is a lesson in lis...